Steerable directional antennas are utilized in numerous applications for communications with the number of applications increasing with new services and needs. For example, steerable directional antennas play a major role in military applications that include synthetic aperture radar systems and phased array communication systems. Also, steerable directional antennas are being increasingly deployed in the commercial arena. As an example, the wireless local area network (WLAN) market is migrating to higher frequency spectra, higher data rates, and higher user densities so that multipath fading and multichannel interference are becoming even more crucial issues. Consequently, the wireless industry is investigating phased array antennas with adaptive control to enhance the data capacity of wireless local area networks.
To illustrate the current technology, a WLAN antenna has been developed for 19 GHz operation by Nippon Telegraph and Telephone Corporation. The antenna is basically a cylindrical twelve-sector antenna that incorporates a complex switching matrix and uses a costly multilayer circuit board fabrication technique to implement the cylindrical phased array. Steerable directional antennas are also being deployed as “smart” antennas, which are phased array antennas with adaptive control. Smart antennas often utilize parallel analog and DSP (digital signal processor) signal processing that tends to be computationally intensive, in which processing complexity increases exponentially with the number of antenna and feed elements.
Consequently, the military and commercial markets have a real need for apparatuses that support steerable directional antennas having desired performance characteristics but that are more cost effective and easier to implement. Relevant design considerations include weight, scan coverage, and the complexity of circuitry that interfaces with the steerable directional antenna.